PV-BESS and Active Power Ramp Rate Control Method thereof
Publication Date: 2016-Sep-06
The IP.com Prior Art Database
HaiLian Xie: AUTHOR [+4]
This disclosure proposes a Photovoltaic – Battery Energy Storage System (PV-BESS) and its active power ramp rate control method, which could be used for: · New developed PV power station that need to meet the active power ramp rate requirements given in standards/grid codes · PV power station with limited cost and footprint for energy storage system.
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PV-BESS and Its Active Power Ramp Rate Control Method Principal Applications/Uses of the Disclosure
This disclosure proposes a Photovoltaic - Battery Energy Storage System (PV-BESS) and its active power ramp rate control method, which could be used for:
· New developed PV power station that need to meet the active power ramp rate requirements given in standards/grid codes
· PV power station with limited cost and footprint for energy storage system
Problem Overcome by the Disclosure
Due to the environmental issue, more and more new energy are used in the power system, e.g. solar power. As an intermittent energy source, the fluctuant solar power might threaten the secure operation and economic dispatch of the power grid as the increased installation. As a result, different Grid Codes have been proposed in order to confine both the steady-state and transient performance of PV power stations, e.g. active power ramp rate etc.
To improve the system performance and increase the accommodation level of solar power, PV-BESS is proposed by many researchers. Regarding to active power ramp rate requirement (one of the important requirements) given in standard/grid codes and economic operation, different control strategies have been proposed for active power ramp rate control of PV-BESS. However, all these control strategies have their limitation and further development is needed.
Problems of PV power station without BESS
Even though a PV power station without BESS could control their positive ramp rates of output power by using proper control strategy to limit its maximum output, the negative ramps due to the sudden decrease of solar radiation are hard to suppress.
Problem of existing active power ramp rate control methods used for PV-BESS
The existing active power ramp rate control methods used for PV-BESS could be summarized as two typical groups: simple feedback control methods and mathematical optimization methods. Both of them output the reference value for BESS power with different calculation procedures/ optimization targets based on:
· the historical values of PV and BESS power
· the forecast values of maximum available PV power (decided by the solar radiation intensity)
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· the current state of charge (SOC) of BESS
These two groups of typical methods differ in control response speed and accuracy due to the use of different calculation methods.
Generally, the simple feedback control methods have fast response due to simpler computation process and known number of computation steps used in the controller. However, the computation schemes are too simple to accurately determine the future BESS power references, which lead to the lowest ramp rate violation probability and maximum solar energy utilization.
The mathematical optimization methods precisely model the determinations of future BESS power references as mathematical optimization problems. And advanced solvers are usually equipped to obtai...